/*包含初始化宏定义的头文件,代码中的module_init和module_exit在此文件中*/
#include <linux/init.h>
/*包含初始化加载模块的头文件,代码中的MODULE_LICENSE在此头文件中*/
#include <linux/module.h>
/*定义module_param module_param_array的头文件*/
#include <linux/moduleparam.h>
/*定义module_param module_param_array中perm的头文件*/
#include <linux/stat.h>
/*三个字符设备函数*/
#include <linux/fs.h>
/*MKDEV转换设备号数据类型的宏定义*/
#include <linux/kdev_t.h>
/*定义字符设备的结构体*/
#include <linux/cdev.h>
/*分配内存空间函数头文件*/
#include <linux/slab.h>

/*包含函数device_create 结构体class等头文件*/
#include <linux/device.h>

#define DEVICE_NAME "chardevnode"
#define DEVICE_MINOR_NUM 2
#define DEV_MAJOR 0
#define DEV_MINOR 0
#define REGDEV_SIZE 3000

MODULE_LICENSE("Dual BSD/GPL");
/*声明是开源的,没有内核版本限制*/
MODULE_AUTHOR("iTOPEET_dz");
/*声明作者*/

int numdev_major = DEV_MAJOR;
int numdev_minor = DEV_MINOR;

/*输入主设备号*/
module_param(numdev_major,int,S_IRUSR);
/*输入次设备号*/
module_param(numdev_minor,int,S_IRUSR);

static struct class *myclass;

struct reg_dev
{
    char *data;
    unsigned long size;

    struct cdev cdev;
};
struct reg_dev *my_devices;
/*打开操作*/
static int chardevnode_open(struct inode *inode, struct file *file){
    printk(KERN_EMERG "chardevnode_open is success!\n");

    return 0;
}
/*关闭操作*/
static int chardevnode_release(struct inode *inode, struct file *file){
    printk(KERN_EMERG "chardevnode_release is success!\n");

    return 0;
}
/*IO操作*/
static long chardevnode_ioctl(struct file *file, unsigned int cmd, unsigned long arg){
    printk(KERN_EMERG "chardevnode_ioctl is success! cmd is %d,arg is %d \n",cmd,arg);

    return 0;
}

ssize_t chardevnode_read(struct file *file, char __user *buf, size_t count, loff_t *f_ops){
    return 0;
}

ssize_t chardevnode_write(struct file *file, const char __user *buf, size_t count, loff_t *f_ops){
    return 0;
}

loff_t chardevnode_llseek(struct file *file, loff_t offset, int ence){
    return 0;
}
struct file_operations my_fops = {
    .owner = THIS_MODULE,
    .open = chardevnode_open,
    .release = chardevnode_release,
    .unlocked_ioctl = chardevnode_ioctl,
    .read = chardevnode_read,
    .write = chardevnode_write,
    .llseek = chardevnode_llseek,
};


/*设备注册到系统*/
static void reg_init_cdev(struct reg_dev *dev,int index){
    int err;
    int devno = MKDEV(numdev_major,numdev_minor+index);

    /*数据初始化*/
    cdev_init(&dev->cdev,&my_fops);
    dev->cdev.owner = THIS_MODULE;
    dev->cdev.ops = &my_fops;

    /*注册到系统*/
    err = cdev_add(&dev->cdev,devno,1);
    if(err){
        printk(KERN_EMERG "cdev_add %d is fail! %d\n",index,err);
    }
    else{
        printk(KERN_EMERG "cdev_add %d is success!\n",numdev_minor+index);
    }
}

static int scdev_init(void)
{
    int ret = 0,i;
    dev_t num_dev;


    printk(KERN_EMERG "numdev_major is %d!\n",numdev_major);
    printk(KERN_EMERG "numdev_minor is %d!\n",numdev_minor);

    if(numdev_major){
        num_dev = MKDEV(numdev_major,numdev_minor);
        ret = register_chrdev_region(num_dev,DEVICE_MINOR_NUM,DEVICE_NAME);
    }
    else{
        /*动态注册设备号*/
        ret = alloc_chrdev_region(&num_dev,numdev_minor,DEVICE_MINOR_NUM,DEVICE_NAME);
        /*获得主设备号*/
        numdev_major = MAJOR(num_dev);
        printk(KERN_EMERG "adev_region req %d !\n",numdev_major);
    }
    if(ret<0){
        printk(KERN_EMERG "register_chrdev_region req %d is failed!\n",numdev_major);       
    }
    myclass = class_create(THIS_MODULE,DEVICE_NAME);


    my_devices = kmalloc(DEVICE_MINOR_NUM * sizeof(struct reg_dev),GFP_KERNEL);
    if(!my_devices){
        ret = -ENOMEM;
        goto fail;
    }
    memset(my_devices,0,DEVICE_MINOR_NUM * sizeof(struct reg_dev));

    /*设备初始化*/
    for(i=0;i<DEVICE_MINOR_NUM;i++){
        my_devices[i].data = kmalloc(REGDEV_SIZE,GFP_KERNEL);
        memset(my_devices[i].data,0,REGDEV_SIZE);
        /*设备注册到系统*/
        reg_init_cdev(&my_devices[i],i);

        /*创建设备节点*/
        device_create(myclass,NULL,MKDEV(numdev_major,numdev_minor+i),NULL,DEVICE_NAME"%d",i);
    }


    printk(KERN_EMERG "scdev_init!\n");
    /*打印信息,KERN_EMERG表示紧急信息*/
    return 0;

fail:
    /*注销设备号*/
    unregister_chrdev_region(MKDEV(numdev_major,numdev_minor),DEVICE_MINOR_NUM);
    printk(KERN_EMERG "kmalloc is fail!\n");

    return ret;
}

static void scdev_exit(void)
{
    int i;
    printk(KERN_EMERG "scdev_exit!\n");

    /*除去字符设备*/
    for(i=0;i<DEVICE_MINOR_NUM;i++){
        cdev_del(&(my_devices[i].cdev));
        /*摧毁设备节点函数d*/
        device_destroy(myclass,MKDEV(numdev_major,numdev_minor+i));
    }
    /*释放设备class*/
    class_destroy(myclass);
    /*释放内存*/
    kfree(my_devices);

    unregister_chrdev_region(MKDEV(numdev_major,numdev_minor),DEVICE_MINOR_NUM);
}


module_init(scdev_init);
/*初始化函数*/
module_exit(scdev_exit);
/*卸载函数*/